Vaccines are almost always a hot-button issue. Who gets which vaccines, when we give them, and whether they are truly safe and effective are all topics that are constantly up for debate among laymen and medical professionals alike. It’s a complex issue, and there is no single right answer given the number of vaccines on the market and the innumerable factors that impact whether a person will experience an immediate, short-term, or long-term reaction to a vaccine. There are, however, a few things everyone should know about vaccines:

The American Academy of Pediatrics has a recommended schedule of fourteen distinct vaccines, some with multiple doses, for children from birth through age 18. You can view and download a PDF of the APA’s recommended vaccine schedule here.

Mild and moderate vaccine reactions are common and, while they vary from person to person and for each vaccine, typically include low-grade fever, soreness and/or warmth at the injection site, muscle and joint pain, nausea, vomiting, diarrhea, dizziness, headache, itching, and rashes.

Severe vaccine reactions are rare but do happen. These include, depending on the vaccine, deafness, death, brain damage, severe pain, bleeding, and serious allergic reactions. Sometimes, severe reactions are delayed, making it very difficult to determine whether the vaccine was, in fact, the root cause of the response. You can read up on the known reactions to any vaccine on the website for the Centers for Disease Control and Prevention.

Not everyone gets vaccinated, and not everyone should. Some people demonstrate serious vaccine reactions, and their doctors determine that for them, the risk of further vaccination outweighs the benefits. Sometimes, a family history within the close family group (parent/child or siblings) will indicate that there is a danger in vaccinating someone. In some cases, doctors recommend a delayed vaccine schedule, for example, when a baby is sensitive to vaccines, the pediatrician may recommend spreading out the shot schedule over a longer period.

The vast majority of Americans are vaccinated, and that means first responders and ER physicians typically presume people are up-to-date on their vaccinations unless told otherwise. Therefore, if you are unvaccinated or only partially vaccinated, it’s important to wear medical ID jewelry that communicates your vaccination status. If you become seriously ill, medical personnel need to know that it’s possible you have an illness for which they would not typically look, polio for example, because most people are vaccinated for it. Additionally, you may need to be quarantined to protect others. Finally, if you’re only partially vaccinated because you have severe vaccine reactions, your vaccine sensitivity is an important piece of your medical history, and it’s something emergency physicians will want to know about right away.